Waterproof fabric with no-slippage features, in particular for offset printing blanket and method for manufacturing the same

Abstract

A waterproof fabric ( 20 ) made such by the application of a protective film ( 10 ), coupled or coated on a side of the fabric ( 20 ). When the film ( 10 ) is already produced by extrusion in advance, it is attached onto the fabric and may comprise an adhesive layer ( 12 ) to the extruded film, or the adhesive layer may be coated on the fabric ( 20 ). The water/oil repellent and waterproof fabric ( 20 ) may also be obtained by coating at least one layer of materials made up of fluorocarbon, polyurethane, acrylic resins, with or without the addition of hollow microspheres of thermoplastic material.

The invention claimed is: 
     
       1. An anti-slip woven fabric having first and second sides and a waterproofing and water/oil-repellant protective film adhered to only one of said sides,
 wherein said protective film is applied to the fabric by: 
 (a) calendaring the fabric layer with a film of polyurethane, polyether, polyester, nylon, polyethylene or polyvinyl chloride, or 
 (b) coating the fabric layer with one or more of a fluorocarbon resin, a polyurethane or an acrylic resin, 
 said protective film having a thickness in the range of from 5 to 100 microns, 
 said protective film, either calendered or coated, weighing from 20 to 30 grams per m 2 , the fabric not being completely impregnated and thereby retaining its intrinsic roughness to prevent slippage as measured by an anti-slip force of between 2.5 and 5.0 grams force when a steel square slide with a roughness (Ra) of 1.5 microns and having 1 inch (25.4 mm) sides and a thickness of 3 mm, moves at a rate of 100 mm/min on the surface of the fabric opposite the protective film, 
 where said protective film is solid and comprises two layers having different thermal resistance values, 
 wherein the first layer applied to the fabric surface has a thermal resistance value selected to ensure secure adhesion to said fabric surface, and wherein the second layer is adhered to the first layer and has a thermal resistance value that has a predetermined solvent resistance and the thermal resistance value of the second layer is selected to provide a softening point between 160° C. and 180° C., and the first layer has a softening point between 110° C. and 130° C. 
 
     
     
       2. A method for producing an anti-slip fabric according to  claim 1 , said method comprising the steps of:
 coating a first layer of waterproofing and water/oil-repellent film comprising resins on one side only of said fabric layer for filling the fabric porosity; 
 in a first heating step, heating said coated fabric layer in a furnace under conditions for drying said first layer without cross-linking the resins; 
 coating said first layer with one or more additional layers of waterproofing and water/oil-repellent film comprising resins; and 
 in a second heating step, heating the coated fabric layer in a furnace under conditions for final cross-linking the resins. 
 
     
     
       3. The method of  claim 2 , wherein in said first heating step the coated fabric layer is moved through a heated chamber approximately 20 m long at a speed of approximately 15 meters a minute, and wherein the temperature within the heated chamber on the fabric is approximately 130° C. 
     
     
       4. The method of  claim 2 , wherein the second heating step takes place at a temperature of approximately 170° C. on the fabric for approximately 2 minutes, for allowing the final cross-linking of the resins. 
     
     
       5. The method of  claim 3 , wherein the second heating step takes place at a temperature of approximately 170° C. on the fabric for approximately 2 minutes, for allowing the final cross-linking of the resins. 
     
     
       6. The method of  claim 2 , wherein at least one of said layers includes non-foamed microspheres, said wherein second heating step comprises the foaming of said microspheres. 
     
     
       7. The method of  claim 2 , wherein prior to the first coating, a washing-purging treatment is carried out on the fabric layer in order to remove any polish and greasy substances which may be present on the fabric, thereby improving the absorption of liquid material. 
     
     
       8. The method of  claim 7 , wherein after said washing-purging step, a calendering of the fabric is carried out. 
     
     
       9. The method of  claim 2 , further comprising the step of measuring the water/oil repellence resistance value of the fabric, assessing the absorption time of one drop of n-decane laid on the fabric surface. 
     
     
       10. The method of  claim 2 , further comprising the step of assessing the anti-slippage characteristics of the fabric using a dynamometer, measuring the force that a steel square slide (with a 25.2 mm side) with 1.5 micron roughness (Ra) and 3 mm thickness encounters n moving at the speed of 100 mm per minute on the surface of the treated fabric. 
     
     
       11. A method for producing an anti-slip fabric according to  claim 1 , comprising the steps of:
 providing a fabric layer having first and second sides; 
 providing a solid waterproofing and water/oil-repellant protective film; and 
 adhering said solid protective film to one of said sides by calendering. 
 
     
     
       12. The method of  claim 11 , wherein said protective film comprises a first and second layer obtained by blown film coextrusion with a steel cylinder heated to a temperature of approximately 120° C. 
     
     
       13. The method of  claim 11 , wherein the calendering is carried out at a pressure between 50 and 100 kg/cm 2 , and at a speed between 3 and 5 meters per minute. 
     
     
       14. The method of  claim 11 , wherein said protective film comprises two layers with different thermal resistances; wherein a first said layer is adhered to said one side of said fabric layer and has a thermal resistance such as to ensure adhesion to said fabric layer, and wherein a second said layer is adhered to said first said layer and has a thermal resistance such as to ensure proper solvent resistance. 
     
     
       15. The method of  claim 14 , wherein said second layer is provided with a thermal resistance (softening point) between 160° C. and 180° C., wherein said first layer is provided with a thermal resistance (softening point) between 110° C. and 130° C. 
     
     
       16. The method of  claim 15 , wherein said solid protective film has a total thickness in the range of 30-80 microns. 
     
     
       17. The method of  claim 16 , wherein said first and second layers have equal thickness. 
     
     
       18. The method  claim 11 , wherein said solid protective film comprises one or more of the following materials: polyurethane, polyether, polyester, or nylon, polyethylene, polyester, polyvinyl or chloride. 
     
     
       19. A printing blanket comprising the anti-slip fabric according to  claim 1 . 
     
     
       20. The printing blanket of  claim 19 , where the anti-slip fabric is the bottom layer.